The goal of this revised proposal is to understand the neurobiology of early learning. Functional changes have been revealed in the olfactory bulb as a consequence of early preference conditioning by means of a technique that records the differential uptake of a glucose analogue. The proposed studies will determine both the precise nature of the cellular changes underlying this increase in metabolism and the specific cells in which these changes are occurring. Glucose pathways will be studied after early olfactory conditioning using three techniques. The first will involve the use of quantitative histochemistry to identify differential metabolic enzyme activity. The second will involve the use of differentially labelled glucose to determine the activation of different metabolic pathways as a consequence of early learning. The third technique will isolate those cells that are particularly active to response to a learned cue by studying the uptake of a glucose analogue, using a high-resolution procedure. The specificity of the cellular pathways, as well as the type of cell involved in the phenomenon will be identified.